fma

 

C

Language

Standard Library

Type support

Dynamic memory management

Error handling

Program utilities

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

 

Numerics

Common mathematical functions

Floating-point environment

Complex number arithmetics

Random number generation

Type-generic math

 

Common mathematical functions

Functions
Basic operations
abslabsllabsimaxabs (C99) fabs divldivlldivimaxdiv (C99) fmod	remainder (C99) remquo (C99) fma (C99) fmax (C99) fmin (C99) fdim (C99) nannanfnanl (C99)(C99)(C99)
Exponential functions
exp exp2 (C99) expm1 (C99)	log log10 log1p (C99) log2 (C99)
Power functions
sqrt cbrt (C99)	hypot (C99) pow
Trigonometric and hyperbolic functions
sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C99) acosh (C99) atanh (C99)
Error and gamma functions
erf (C99) erfc (C99)	lgamma (C99) tgamma (C99)
Nearest integer floating point operations
ceil floor roundlroundllround (C99)(C99)(C99)	trunc (C99) nearbyint (C99) rintlrintllrint (C99)(C99)(C99)
Floating point manipulation functions
ldexp scalbnscalbln (C99)(C99) ilogb (C99) logb (C99)	frexp modf nextafternexttoward (C99)(C99) copysign (C99)
Classification
fpclassify (C99)
isfinite (C99)
isinf (C99)
isnan (C99)
isnormal (C99)
signbit (C99)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C99)(C99)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99)

 

Defined in header <math.h>
float       fmaf( float x, float y, float z );		(since C99)
double      fma( double x, double y, double z );		(since C99)
long double fmal( long double x, long double y, long double z );		(since C99)

The fma functions compute (x*y) + z, rounded as one ternary operation, according to the rounding mode characterized by the value of FLT_ROUNDS.

Parameters

x, y, z

-

floating point values

Return value

(x*y) + z, rounded as one ternary operation

Example

Run this code

#include <stdio.h>
#include <math.h>
 
int main()
{ 
    #ifdef FP_FAST_FMAF
        printf("FP_FAST_FMAF defined\n");
    #else
        printf("FP_FAST_FMAF undefined\n");
    #endif
    #ifdef FP_FAST_FMA
        printf("FP_FAST_FMA  defined\n");
    #else
        printf("FP_FAST_FMA  undefined\n");
    #endif
    #ifdef FP_FAST_FMAL
        printf("FP_FAST_FMAL defined\n");
    #else
        printf("FP_FAST_FMAL undefined\n");
    #endif
 
    /* Expect the software version to be slower. */
    printf("fma(2.0,3.0,1.0) = %f\n", fma(2.0,3.0,1.0));
 
    return 0;
}

Possible output:

FP_FAST_FMAF undefined
FP_FAST_FMA  undefined
FP_FAST_FMAL undefined
fmaf(2.0,3.0,1.0) = 7.000000

See also

remainder (C99)	signed remainder of the division operation (function)
remquo (C99)	signed remainder as well as the three last bits of the division operation (function)
C++ documentation for fma